Medical Bionics - Theses

Permanent URI for this collection

http://hdl.handle.net/11343/45240

Filters

2023 1
1
Reset filters

Settings
Statistics
Citations
Subject: Parkinson's disease × Author: Sinclair, Nicholas Campbell ×

Search Results

Now showing 1 - 1 of 1
  • Item
    Thumbnail Image
    Deep brain stimulation evoked resonant neural activity
    Sinclair, Nicholas Campbell ( 2023-02)
    Deep brain stimulation (DBS) involves surgically implanting electrodes within targeted subcortical structures and applying chronic electrical stimulation to produce therapeutic effects. DBS has utility for a range of movement and psychiatric disorders, with DBS of the subthalamic nucleus (STN) for the treatment of Parkinson’s disease a common application. Although DBS can be remarkably effective, several challenges can limit its application and efficacy, including 1) the target neural structures are very small and challenging to accurately implant with electrodes; 2) DBS implantation surgery commonly requires the patient to be awake; 3) selection of beneficial stimulation parameters for chronic therapy is a laborious manual process prone to suboptimal outcomes; 4) chronic therapy is applied constantly regardless of the patient’s present therapeutic needs; and 5) the mechanisms of action of DBS are yet to be fully elucidated. Electrophysiological feedback signals may provide the means for addressing these challenges. A signal localised to the target neural structure could be used like a homing beacon to guide electrode implantation and configuration for chronic therapy. Furthermore, if the signal was measurable under general anaesthesia, it could be used to guide implantation in unconscious patients. A signal that varies with patient symptomatic state and the application of DBS could also guide selection of stimulation parameters, inform on mechanisms of action, and act as a feedback signal for monitoring patient state in real-time and automatically adapting stimulation settings to optimise therapy. This thesis identifies a novel evoked potential – termed evoked resonant neural activity (ERNA) – elicited by DBS pulses applied in the vicinity of the STN and investigates its potential for improving DBS therapy. ERNA is confirmed to be of neural origin and is shown to have largest amplitude in the dorsal subregion of the STN, where DBS for Parkinson’s disease is typically most effective. ERNA and its localisation are also shown to be present and readily measurable under general anaesthesia. Additionally, both the frequency and amplitude of ERNA are shown to vary with the application of therapeutically-effective DBS. The characteristics of ERNA make it an electrophysiological signal with considerable potential for addressing the challenges associated with applying DBS therapy, particularly STN-DBS. ERNA’s localisation to dorsal STN and presence under anaesthesia indicate utility in guiding electrode implantation and configuration in both awake and unconscious patients. Variation in ERNA with therapeutically-effective DBS also indicates potential utility in guiding the selection of chronic stimulation parameters, investigating mechanisms of action, and automatically adapting therapy according to the patient’s real-time needs.